The chief question raised seems to be does tradition come before religion or vice-versa?

In truth present day suicide bombers and the like are an extension of the self-abnegatory courage which is a sine qua non of fighting in battle.

Most British infantrymen boarding trains for the front knew the statistical chances of their coming back alive.

Dogged, numbing determination to conquer fear is a male trait evolved for emergencies. To fear death was ignoble and unbecoming, you were expected to feign bravery and have total control over your muscular and excretory systems to be accepted into the brotherhood of combat. Such is the power of the trained human will combined with peer coercion that whole troops can be brainwashed to feel this way, especially with judicious use of drugs such as amphetamine, benzidrine and the like, which cut us off from the tender parts of our characters and make us feel temporarily, cavalierly invincible.

Obviously the stress of maintaining this level of psychological stress for long campaigns plays merry hell with the adrenal and nervous systems. Many went mad with the contradictions, shell shock was common. My grandfather, veteran of two world wars was a walking example.

So we're hardwired for dissociation.

People commit suicide when they see no way things will improve. Many take others down with them for no reason other than bile, almost daily in Gun Nirvana stateside.

So it's easy to put these traits together and semi-rationally explain the phenomenon. Bribe a poor young ghetto kid with a some money for his descendants, fire up his religious circuits (Paradise!) and his carnal ones (72!). Tell him instead of being another anonymous cipher he'll be a legend in his community, and recruiting them is probably easier than most western minds can allow ourselves to think.

Anthropology and archeology try to give us answers to which came first, tradition or religion, inconclusively so far. Patriotism, tribal pride, bellicose music all have been used to get men to keep going straight into the mouth of hell even when every cell in their bodies was screaming danger, abort!

Now it's the name of a sky god. It is interesting how much our wills can over-ride our desire for survival.
Grandpa would have walked off a cliff if the King had asked it of him, it was his duty as an Englishman, "Ours not to reason why, ours but to do or die".

Jim Jones laid a deathwish spell on himself and thousands of followers submissively complied.

There's only one letter difference between thanatic and fanatic, life is very, very cheap in some parts of the world. Almost three generations in Europe have lived without war on our doorsteps, coddled in consumer comfort, in the main we have completely forgotten what it meant to have to die for a cause one believed in more than life itself, and do try and do so with serene aplomb if we could.

It's the thorniest of present-day problems. Millions of dollar-think-tank-man-hours are going into the intricate psychological niceties of why someone would do such a thing.
Occam's razor leads me to believe the human race uses war and violence as a form of self-culling. Those most adapted to continued violence are thus removed from the gene pool before they reproduce, possible creating beings even and ever more attracted to violence. Stupidly simplistic certainly, but it has a Darwinian tidiness to it.

Lastly the paradox of how more soldiers commit suicide after returning from battle than do on the field speaks volumes about this issue...

Religion and tradition, which is chicken, which is egg?

'The history of public debt is full of irony. It rarely follows our ideas of order and justice.' Thomas Piketty